1. Field of the Invention
Priority is claimed on Japanese Patent Application No. 2003-400400, filed Nov. 28, 2003, the contents of which are incorporated herein by reference.
The present invention relates to an image display apparatus for displaying a monochrome image comprising a backlight unit that is provided with a plurality of light sources and an image display panel that is placed in front of the backlight unit.
2. Description of Related Art
Recent years have seen a rapid change in display apparatuses from those that use CRT as display devices to those that use liquid crystal panels as display devices. The most common display apparatuses that use liquid crystal panels as a display device (hereinafter, referred to as liquid crystal display apparatuses) are those that have light sources on a rear surface of a display panel (i.e., of a liquid crystal panel). Fluorescent lamps are often used for the light sources used in these liquid crystal display apparatuses. Fluorescent lamps characterized by having three wavelengths, namely, red, green, and blue (i.e., three wavelength fluorescent lamps) are used, and an optional color (i.e., chromaticity) is made by combining the respective wavelengths. However, even if a plurality of fluorescent lamps are used in a liquid crystal display apparatus, all of the fluorescent lamps that are used have the same luminescent color.
Moreover, among conventional liquid crystal display apparatuses, in order to solve the problem of it not being possible to easily adjust chromaticity, a liquid crystal display apparatus has become known that enables chromaticity adjustment, which has been difficult in a conventional liquid crystal display apparatus, to be performed inside a liquid crystal module using only an internal circuit extension of a controller (see for example Japanese Patent Application Laid-Open (JP-A) No. 2001-282190).
However, because all of the fluorescent lamps that are used have the same luminescent color even if a plurality of fluorescent lamps are used in a liquid crystal display apparatus, the problem has existed that it has not been possible to change the display screen chromaticity of the liquid crystal display apparatus.
Moreover, because the fluorescent materials corresponding to red, green, and blue that are used in the fluorescent lamps are different, the degree of deterioration when the fluorescent lamps are used for an extended period of time (i.e., changes of the time) is different in each. As a result, the emission intensity (i.e., the quantity of light) for each of red, green, and blue decreases at a different rate, and the ratios of the light generation intensities of the red, green, and blue that are emitted from the fluorescent lamps change. Therefore, the luminescent colors of the fluorescent lamps end up changing, resulting in the problem arising that the display screen chromaticity of the liquid crystal display apparatus also changes.
The present invention was conceived in view of the above circumstances, and it is an object thereof to provide an image display apparatus that enables the display screen chromaticity of the display apparatus to be adjusted to the chromaticity desired by the user.
It is a further object of the present invention to provide an image display apparatus that enables the display screen chromaticity to be kept substantially uniform by correcting changes in the luminescent color of the light source that are caused by the length of time the display apparatus is used for.